 Following graduation he worked as an assistant to Karl Ludwig Kahlbaum at the mental hospital in Görlitz, and in 1887 became an assistant to Otto Binswanger at the psychiatric clinic in Jena.At Jena one of his patients was philosopher Friedrich Nietzsche.Subsequently he was a professor of psychiatry in Utrecht (from 1900), Halle (from 1903) and Berlin (1904–1912).